首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   33000篇
  免费   1618篇
  国内免费   210篇
耳鼻咽喉   347篇
儿科学   666篇
妇产科学   365篇
基础医学   4308篇
口腔科学   744篇
临床医学   2211篇
内科学   8841篇
皮肤病学   539篇
神经病学   2438篇
特种医学   1372篇
外科学   5220篇
综合类   126篇
一般理论   2篇
预防医学   826篇
眼科学   545篇
药学   2327篇
中国医学   109篇
肿瘤学   3842篇
  2023年   185篇
  2022年   315篇
  2021年   741篇
  2020年   384篇
  2019年   515篇
  2018年   653篇
  2017年   506篇
  2016年   627篇
  2015年   670篇
  2014年   829篇
  2013年   1085篇
  2012年   1696篇
  2011年   1914篇
  2010年   1036篇
  2009年   876篇
  2008年   1602篇
  2007年   1840篇
  2006年   1668篇
  2005年   1801篇
  2004年   1727篇
  2003年   1618篇
  2002年   1653篇
  2001年   855篇
  2000年   876篇
  1999年   824篇
  1998年   475篇
  1997年   367篇
  1996年   366篇
  1995年   317篇
  1994年   321篇
  1993年   277篇
  1992年   593篇
  1991年   603篇
  1990年   545篇
  1989年   524篇
  1988年   411篇
  1987年   373篇
  1986年   386篇
  1985年   356篇
  1984年   254篇
  1983年   217篇
  1982年   137篇
  1981年   115篇
  1980年   125篇
  1979年   187篇
  1978年   134篇
  1977年   120篇
  1974年   115篇
  1972年   106篇
  1968年   103篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.

Background

Photosensitizers used for photodynamic therapy (PDT) to treat dermatologic disease are metabolized into mainly protoporphyrin IX (PpIX), which has five absorption wavelength peaks: 410?nm, 510?nm, 545?nm, 580?nm, and 630?nm. Although only red light around 635?nm and blue light around 400?nm are used as light sources for PDT, the efficiency of PDT might be improved by using multiple wavelengths, including those that correspond to the other absorption peaks of PpIX. Furthermore, because the target disease often occurs on the face, a flexible-type light-source unit that can be fitted to the lesion without unnecessarily exposing the mucous membranes, e.g., the eyes, nostrils, and mouth, is preferred.

Objective

We investigated the efficacy of a flexible light-emitting diode (LED) unit that emits multiple wavelengths to improve PDT effects.

Methods

HaCaT cells were incubated with 5-ALA and subsequently irradiated with either a single wavelength or sequentially with two wavelengths. Cell viability and reactive oxygen species were analyzed. Nude mice were implanted with COLO679 cells by subcutaneous injection into the flank. 5-ALA was subcutaneously injected into the tumor. The tumor was irradiated with 50?J/cm2 (day 0) and assessed daily until day 21.

Results

The synergistic PDT effects of dual-wavelength irradiation and reactive oxygen species production were highest with the 405-nm and 505-nm wavelength combination. This dual wavelength combination was also the most effective in vivo.

Conclusion

We could therefore conclude that dual-wavelength PDT is an efficient strategy for improving the therapeutic effects of PDT. Using a flexible LED unit is expected to achieve more uniform irradiation of uneven areas.  相似文献   
2.
3.
4.
5.
6.

Background

There were few studies assessed the postoperative sarcopenia in patients with cancers. The objective of present study was to assess whether postoperative development of sarcopenia could predict a poor prognosis in patients with adenocarcinoma of esophagogastric junction, (AEG) and upper gastric cancer (UGC).

Methods

Patients with AEG and UGC who were judged as non-sarcopenic before surgery were reassessed the presence of postoperative development of sarcopenia 6 months after surgery. Patients were divided into the development group or non-development group, and clinicopathological factors and prognosis between these two groups were analyzed.

Results

The 5-year overall survival rates were significantly poorer in the development group than non-development group (68.0% vs. 92.6%, P?=?0.0118). Multivariate analyses showed that postoperative development of sarcopenia was an independent prognostic factor for poor overall survival (P?=?0.0237).

Conclusions

Postoperative development of sarcopenia was associated with a poor prognosis in patients with AEG and UGC.  相似文献   
7.
<正>Stroke is a leading cause of mortality and severe neurological disability worldwide; however, curative therapeutic options are limited. Although recanalization therapy using endovascular thrombectomy has demonstrated great benefits in the functional outcome of patients with acute ischemic stroke, the rate of excellent clinical outcomes remains limited. Therefore, the current recanalization  相似文献   
8.
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号